(a) Field of the Invention
The present invention relates in general to an improved structure of a pipe fitting, and particularly to the structure of a quick-connect pipe fitting for connecting piping or hydraulic tubing.
(b) Description of the Prior Art
A conventional quick-connect pipe fitting is shown in FIG. 6. Such fitting mainly includes a quick-connect fitting body 10, a seal washer 20, a lock washer 30, a base 40 and a pressurized washer 50. The fitting is used for connecting a plastic pipe 60 in a pressurized or hydraulic system. The lock washer and the seal washer lock and seal the pipe connection in an air-tight system. To disconnect this conventional pipe fitting, the pressurized washer 50 has to be pushed down to touch the lock washer and open up the inner teeth of the lock washer. Since the diameter of the ring-shaped pressurized washer 50 is very small, and the lock washer has a very high locking strength, it is not easy to push down the pressurized washer. The pressing is uncomfortable for the fingers. In addition, a majority of the pressurized washers today are made out of plastic materials, and they tend to lock dead after a period of time due to the teeth marks on the inner wall of the pipe. Pushing the pressurized washer down with too much force can crack or break the plastic washer making it necessary to shutdown the pressurized system to replace the pipe fitting.
In addition, the above conventional quick-connect pipe fitting is directly connected to a vent tube through the threads at the end of the fitting body. Therefore, air flow can always pass through the pipe fitting to the vent tube. The conventional pipe fitting does not provide a mechanism to close the air flow. After the conventional quick-connect pipe fitting is connected to a pressure pipe, the valve has to be opened for servicing. This is inconvenient. Moreover, when a main pipe is branched out to several service locations, all the quick-connect pipe fittings have to be connected on both sides before the main valve can be opened for servicing. The addition of an individual shutoff valve to each line with a quick-connect pipe fitting is costly and creates more work in operation.